Electrical-thermal-fluidic coupling Li-ion battery pack consistency study

The thermal effect of lithium (Li)-ion batteries affects its performance and service life and threatens its safety. Therefore, a new tree-shaped channel heat sink was developed for cooling Li-ion battery packs and compared with fractal and serpentine channel heat sinks. Moreover, the electrical-thermal-fluidic multi-physics simulation was implemented based on the equivalent circuit model. The temperature distribution effect on the battery pack's consistency was investigated. Different circuits were established through various series-parallel topologies, and the battery pack's discharging and temperature characteristics were examined when the cells' initial parameters were different. The results demonstrated that the new tree-shaped channel heat sink offered effective heat dissipation and small flow resistance. The decreasing temperature difference enhanced the current consistency, while the decreasing temperature rise reduced the voltage consistency. The series or parallel connection between the battery modules slightly affected the battery pack's discharging and temperature characteristics. Within the module, a reduction in the number of batteries in series or augmentation in the parallel branches reduced the battery consistency and increased the battery pack's average temperature rise and temperature difference. The battery consistency in the parallel-first topology module was better than that in the series-first topology module under the same number of parallel branches. These results are helpful for the battery pack consistency studies.